If a client connect to a storage more than one time, cut the old connection
and replace it by the new one. This is required if the client reconnect to
fast and the storage handle in single poll loop the new connection *then*
the lost of the previous connection.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2195 71dcc9de-d417-0410-9af5-da40c76e7ee4